^^;;;;;
If we except one combat inept mage, and consider the sum of OB, DB and any possible one-round bonus (any bonus that the character may be able to activate in one round, including a magical item or a spell), for my 17th level NPCs, it ranges from 223 for the less combat-able mage to 489 for the combat-oriented semi-spell user. Well, to be true, I have one 17th level warrior-monk that totals 561, but then she's considered a cheater and a game-breaker in-universe, even by the gods, who still let her go away with it because they think she's yet too awesome (to have been able to cheat that much to reach such a level), so I guess she doesn't really count. :p
Breaking the figures, the OBs go from +133 to +285 (aforementioned Uranie), the DBs from 48 to 142, and the one-round bonus from +10 (probably the simple Blur) to +130 (of course, the Paladin's Holy Avenger spell, the monstrous spell that adds +100 ot OB, +30 to DB, is instant and lasts 1 round per level).